Fuel injection pump



Oct.l 15,1968 G.HOEFER 33?405,700

FUEL INJECTION PUMP Filed June 1, 1966 4 Sheets-Sheet l lf 3g 31a fg 33a31! 27 1855 PI Z .x f l 23 -l L, xv. @SLW 23a l 73 3c l 351:5 "33 Oct.l5, 1968 G. HQEFER 3,405,700'

FUEL INJECTION PUMP Filed June l, 1966 4 Sheets-Sheet 2 Oct. l5, 1968 G.HOEFER 3,405,700

FUEL INJECTION vPUMP l l y r.

RMZ 7 J3 MM@ 37 3! 3.5 3 5255/ "m lf//f/f/ 0 'R275 31 E55 Oct. 15, 1968G. HOEFER 3,405,700

FUEL INJECTION PUMP Filed June 1, 1966 4 Sheets-Sheet 4 G'crald HWUnited States Patent O 19,127 6 claims. (ci. 12s- 140) ABSTRACT OF THEDISCLOSURE A fuel injection pump for internal combustion engines inwhich injection of fuel to the cylinders of the engine is interrupted atleast after the engine has reached its maximum speed by a regulatingvalve reciprocatable in axial direction and turnable about its axis andwhich is provided with a peripheral controlling face extending in partinclined to its axis and controlling, depending on the axial and angularposition of the valve, a relief channel communicating with the workingchamber of the pump, in which the valve is moved in one direction byfuel displaced by an auxiliary pump operating in synchronism with thepiston of the injection pump and in the opposite direction by elasticmeans, and including means operatively connected to the valve forchanging the angular position of the latter as a function of therotational speed of the engine.

The present invention relates to fuel injection pumps, and moreparticularly to improvements in fuel injection pumps of the typedisclosed in Patents Nos. 3,044,404 and 3,122,100 to Bessiere. Stillmore particularly, the invention relates to improvements in theconstruction and operation of devices which can regulate the quantitiesof fuel admitted by a fuel injection pump to the cylinder or cylindersof an internal combustion engine.

The aforementioned patents to Bessiere -disclose a fuel injection pumpwherein a main piston performs alternating working and suction strokesto respectively expel fuel from and to draw fuel into a working chamber.The main piston not only reciprocates but also rotates at a speed whichis synchronized with the rotational speed of the internal combustionengine, land its angular movement is utilized to distribute meteredquantities of fuel to the cylinders of the engine. The Bessiere fuelinjection pump further comprises a regulating valve which is movableback and forth in response to the action of a return spring and inresponse to the pressure o-f fuel supplied by an auxiliary pump whosefuel displacing element operates in synchronsm with the main piston. Thevalve is utilized to regulate the quantities of fuel which lare injectedinto the cylinders durnig starting and at different rotational speeds ofthe engine. The principle underlying the operation of such regulatingvalve is known as a liquid abutment or liquid stop and can be defined asincluding such adjustment in the strokes of the valve in response todifferent rotational speeds o-f the engine that the valfve will open anoverflow channel from the working chamber at an earlier or later stagewhile the main piston performs a working stroke whereby the fuel whichis expelled from the working chamber finds the path of least resistanceand escapes through the overflow channel rather than opening a checkvalve in the fuel line which connects the working chamber with theinjection nozzle of a cylinder in the internal combustion engine.

It was -found that the just described fuel injection pump requiresfurther important improvements, especially as regards the selection ofvarious stages in operation of the engine when the regulating valvepermits escape of fuel ice through the overflow channel in order toinsure that, for example, when the engine operates at full load; itscylinders will invariably receive such quantities of fuel as are needed,at any desired rotational speed, to produce a fuel-air mixture Whichburns without the generation of smoke. The Bessiere pump must beprovidedwith an adjustable throttle which controls the return flow offuel from the chamber of the regulating valve, and the throttle -rnustbe adjusted for each rotational speed. Such continuous adjustment isundesirable when the engine is built into an automotive vehicle.Furthermore, the regulating action during certain stages of theoperation should not be dependent on the rotational speed of the engineand such mode of operation of heretofore known fuel injection pumps canbe achieved only by resorting to relatively complicated and sensitiveauxiliaries.

Accordingly, it is an important object of my in'vention to provide animproved fuel injection pump of the type wherein the quantity of fuelwhich is expelled from the working chamber during a Working stroke ofthe main piston may be regulated by a valve operating on the principleof liquid abutment.

Another object of the invention is to provide a fuel injection pump ofthe just outlined characteristics wherein the regulating Valve isadjustable in response to changes in rotational speed of or in responseto changes in load upon the engine in which the pump is being used andwherein the regulating valve may perform a composite movement whichincludes axial amovement and an additional movement, both such movementsbeing utilized to determine the exact quantity of fuel which can beexpelled from the working chamber of the cylinders of an internalcombustion engine.

A further object of the invention is to provide a novel control unitwhich can regulate the additional movement of the regulating valve.

Another object of the instant invention is to provide a fuel injectionpump which occupies very little room, which can be built into orcombined With existing internal combustion engines, which can`distribute fuel to engines having one or more cylinders, and which canbe readily adjusted so that it can be built into different types ofinternal combustion engines.

A concomitant object of the present invention is to provide a fuelinjection pump wherein the regulating valve may be adjusted in aplurality of ways and wherein at least two such adjustments are fullyautomatic.

A further object of my invention is to provide a fuel injection pumpwhich operates on the principle of liquid abutment and wherein theregulating valve is not only operated but is also constructed in a novelway.

Briefly stated, one feature of my invention resides in the provision ofa fuel injection pump for supplying metered but variable quantities offuel to one or more cylinders of an internal combustion engine. The fuelinjection pump comprises a source of fuel which preferably includes afuel tank and a supply conduit provided with a fuel pump which is drivenby the engine to produce a fuel pressure proportional to the rotationalspeed of the engine, housing means having a main chamber or workingchamber and a relief channel which is connected to the working chamberand may be arranged to return surplus fuel back to the source or into asuction space of the housing means, a regulating V chamber provided inthe relief channel, a supply conduit adapted to connect the source (forexample, the aforementioned suction chamber) with the working chamlberin the housing means, at least one discharge conduit adapted to connectthe working chamber with a cylinder of the engine, a main pistonymovable n the housing means to perform alternating suction and workingstrokes to thereby respectively draw fuel from the source into theworking chamber through the supply conduit and to expel fuel from theworking chamber through the discharge conduit or conduits and/or throughthe relief channel, drive means for rotating and reciprocating the mainpiston at a rate proportional to the rotational speed of the enginewhereby the reciprocatory movement of the main piston results inadmission and expulsion of fuel from the working chamber while theangular movement brings about distribution of fuel to one or moredischarge conduits, a regulating valve installed in the regulatingchamber for angular and axial movement therein to thereby control theflow of fuel from the working chamber through the relief channel, anauxiliary pump having a fuel displacing element operating insynchronisrn with the main piston to feed fuel into the regulatingchamber during working strokes of the main piston and to thereby effectaxial movement of the valve against the opposition of a suitable returnspring tending to maintain the valve in a starting axial position, andcontrol means including a device lfor changing the angular position ofthe valve as a function of the rotational speed of the engine,preferably as a function of the pressure generated by the aforementionedfuel pump. Of course, and since the pressure of this pump is function ofthe rotational speed of the engine, such rotational speed indirectlycontrols angular movements of the valve in the regulating chamber.

The valve is provided with a peripheral regulating face which canregulate the flow of fuel between two prtions of the relief channel inresponse to axial and/or angular displacement of the valve withreference to the housing means, the two portions of the relief channelbeing separated from each other by the regulating charnber.

The valve seals the relief channel during starting of the engine so thateach cylinder of the engine then receives a maximum quantity of fuel. Onthe other hand, at least when the engine is driven at a maximumrotational speed, the regulating chamber receives fuel from theauxiliary pump at such a rate that the valve cannot return to startingposition during each suction stroke of the main piston whereby therelief channel invariably allows escape of at least some fuel from theworking chamber while the main piston performs a working stroke. Suchaction of the regulating valve constitutes the aforediscussed liquidabutment.

The control means may further include a manually adjustable actuatingmember which can bring about changes in angular position of theregulating valve. The aforementioned device of the control meanspreferably includes a control cylinder one chamber of which is connectedwith the pressure side of the fuel pump, a control -piston which isreciprocable in the control cylinder and tends to move in one directionin response to rising fuel pressure, an operative connection between thecontrol piston and the regulating valve to change the angular positionof the valve in response to axial movement of the control piston, andresilient means including at least two springs which oppose the fuelpressure acting against the control piston with differences forces. Thecontrol means also includes means for adjusting or changing the force ofat least one suc-h spring.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved fuel injection pump itself, however, both as to itsconstruction and its mode of operation, together with additionalfeatures and advantages thereof, will be best understood upon perusal ofthe following detailed description of certain specic embodiments withreference to the accompanying drawings, in which:

FIG. 1 is a central section through a fuel injection pump which embodiesone form of my invention;

FIG. 2 is a diagram showing relative positions of the regulating valveand the inlet of a portion of the relief channel in different angularpositions of the valve;

FIG. 3 is a diagram showing the relationship between the quantities offuel which are injected into the cylinders of an internal combustionengine and the angular position of the regulating valve;

FIG. 4 is a diagram whose curve illustrates variations in fuel pressureas a function of the rotational speed of the engine;

FIG. 5 illustrates in section certain components of the control unitwhich adjusts the angular position of the regulating valve;

FIG. 6 illustrates the structure of FIG. 5 with its components inpositions they assume when the engine is at a standstill;

FIG. 7 shows the pants of FIG. 5 or 6 in positions they assume when theengine is idling;

FIG. 8 shows the structure of FIG. 7 but with the parts in positionsthey assume when the engine is running under partial load;

FIG. 9 shows the same structure with the parts in positions they assumewhen the engine operates at full load;

FIG. l0 again shows the same structure with the parts in positions theyassume when the engine operates at full load `and at maximum rotationalspeed;

FIG. l1 illustrates the same structure as FIGS. 5 to 10 but showing theparts in positions they assume when the operator decides to arrest theengine;

FIG. 12 is a diagram showing different stages in operation of the fuelinjection pump fwhich is illustrated in FIGS. 1 and Stoll;

FIG. 13 is a section through a modified control unit for the regulatingvalve of the fuel injection pump shown in FIG. l;

FIG. 14 is a diagram showing the relationship between the quantity ofinjected fuel and the rotational speed of the engine which embodies thestructure of FIG. 13;

FIG. 15 is a similar diagram showing the relationship between thequantity of injected fuel and the angular position of the regulatingvalve which is controlled by the unit of FIG. 13; and

FIG. 16 is a diagram similar to that of FIG. 14 but showing a differentrelationship between the rotational speed and the quantity of injectedfuel.

` Referring first to FIG. 1, there is shown a fuel injection pump whichcomprises a housing 1 having a composite blind bore 1a receiving amulti-stage piston 1b. The piston 1b comprises a smaller-diameter firststage 4 (hereinafter called main piston) Iwhich is slidable androtatable in the housing 1 and defines therewith a working chamber 2constituting the innermost part of the bore 1a. The larger-diametersecond stage 5 of the multi-stage piston 1b constitutes the liquiddisplacing element of an auxiliary pump and defines with the housing 1an auxiliary pump chamber 3 occupying that portion of the bore 1a whichis adjacent to its open end. The multi-stage piston 1b is driven by thedrive D of an internal combustion engine E so that it performs acomposite movement including a reciprocatory movement (arrow 1c) and arotary movement (arrow 1d). The drive D which moves the multi-stagepiston 1b preferably includes a cam and follower unit (not shown) whichmay be of the type as disclosed in the copending application Ser. No.538,664 of Eheim, now Patent No. 3,333,542. The main piston 4 serves todistribute metered quantities of fuel t0 the cylinders of the engine E.

The housing 1 further defines a suction space 6 which is connected witha tank 1e or another suitable source of fuel. The feed conduit 27 whichconnects the tank le with the suction space 6 contains a fuel pump 7.The pressure produced by the pump 7 is a function of the r.p.m. of theengine E. The operative connection between the drive D and the fuel pump7 is indicated in FIG. l by a phantom line.

The supply conduit Iwhich can deliver fuel from the suction space 6 tothe working chamber 2 comprises a bore 8 connecting the suction space 6with the smallerdiameter portion of the blind bore la, a circumferentialgroove 9 in the periphery of the main piston 4, and an axially extendingbore 10 provided in the main piston 4 and communicating with the groove9. The outlet of the bore 8 is positioned in such a way that it can besealed by the main piston 4 when the latter performs a working stroke,i.e., while the main piston moves upwardly as viewed in FIG. 1 to expelfuel from the Working chamber 2. The inner end portion of the mainpiston 4 is formed with an axially extending peripheral groove 11 whichforms part of the discharge conduit and is in permanent communicationwith the working chamber 2. This axial groove 11 terminates short of thecircumferential groove 9 and communicates seriatim with a plurality offuel lines 12 (only one shown in FIG. 1) leading to the fuel injectionnozzles (not shown) of the individual cylinders in the engine E.The'intake ends of the fuel lines 12 are distributed uniformly aroundthe circumference of the main piston 4 and each thereof contains aone-way valve here shown as a ball check valve 12a. During each of itsworking strokes, the main piston 4 places its axial groove 11 intocommunication lwith a different fuel line 12. The fuel lines 12 formwith the axial groove 11 the aforementioned discharge conduit whichserves to convey fuel expelled from the working chamber 2 intoconsecutive cylinders of the engine E.

The Working chamber 2 communicates with a relief channel which evacuatesfrom this working chamber any surplus fuel that should not be admittedto the cylinders of the engine E. The relief channel comprises two bores14, 16 which are separated from each other by a regulating chamber 15.The outlet of the relief bore 14 communicates with the regulatingchamber 15 which latter accommodates a rotary slide valve 13 serving toregulate the quaitity of fuel that is actually admitted into thecylinders of he engine E. The valve 13 (hereinafter called regulatingvalve) is formed with a circumferential groove 17 extending between twocylindrical portions or plungers 13a, 13b. The relief bore 16 connectsthe regulating chamber 15 with the suction space 6 but its inlet 39 canbe sealed from the chamber 15 by the right-hand plunger 13b. A bypassbore 40 also connects the suction space 6 with the regulating chamber 15but its intake end can be sealed by the left-hand plunger 13a. Thecircumferential groove 17 is in permanent communication with the reliefbore 14 and its right-hand axial end is bounded by a speciallyconiigurated regulating face 18 of the plunger 13b. The configuration ofthe regulating face 18 Iwill be described in connection with FIG. 2. Theplungers 13a, 13bl are fluid-tightly but slidably fitted into theregulating chamber 15 and the regulating valve 13 is permanently biasedby a strong return spring 19 which tends to maintain a collar 13e of thevalve 13 in abutment with the adjoining internal surface 1f of the pumphousing 1. When the collar 13C abuts against 'the surface 1f, the inlet39 of the relief bore 16 is sealed by the plunger 13b.

The fuel displacing element 5 and the adjoining portion of the housing 1together form the aforementioned auxiliary pump whose purpose is toshift the regulating valve 13 against the bias of the return spring 19.Such displacement of the regulating valve 13 will Itake place inresponse to expulsion of fuel from the auxiliary chamber 3. Theconnection between the chambers 3 and 15 comprises a duct 21 which is abore machined into the housing 1 and contains a check valve 22. The mainpiston 4 will cease to deliver fuel into one of the fuel lines 12 whenthe fuel expelled from the auxiliary chamber 3 via duct 21 and enteringthe left-hand end of the regulating chamber 15 shifts the regulatingvalve 13 to such an extent that the relief bore 14 is free tocommunicate with the bore 16, i.e., when the regulating face of theplunger 13b exposes at least a portion of the inlet 39. The fuelescaping from the working chamber 2 then follows the path of leastresistance and, instead of overcoming the resistance of a check valve12a, flows through the relief bore 14, groove 17, inlet 39, theremainder of the bore 16, and back into the suction space 6.

The auxiliary chamber 3 can receive fuel through a suction port 20 whichconnects to the suction space 6. The fuel displacing element 5 allowsthe suction port 20 to communicate with the chamber 3 when themulti-stage piston 1b reaches the end of its suction stroke.

During each interval between two successive working strokes of the fueldisplacing element 5,1the spring 19 tends to return the regulating valve13 to the starting position of FIG. l in which the collar 13a` abutsagainst the internal surface 1f. The plunger 13a then expels fuel fromregulating chamber 15 and such fuel flows through a duct 23 whichbypasses the one-way valve 22 in the duct 21. Return ow of fuel throughthe duct 23 can be regulated by a. throttle 24 having a needle likethrottling member 25 which is adjustable by a linkage 49a in a manner tobe fully described hereinafter. The throttling member 25 can impede thereturn flow of fuel from the regulating chamber 15 to such an extentthat the fuel displacing element 5 performs the next working strokebefore the valve 13 returns all the way to the starting position ofFIG. 1. In other words, in a certain range of rotational speeds of theengine E, the regulating valve 13 cannot return to starting positionafter each successive working stroke of the main piston 5. This meansthat the fuel lines 12 will receive lesser quantities of fuel becausethe valve 13 will establish a connection between the relief bores 14 and16 in response to admission of a relatively small quantity of fuel intothe chamber 15. This so-called liquid stop or liquid abutment is fullydisclosed in the aforementioned Patent No. 3,044,404 to Bessiere. Inother words, and when the rotational speed of the engine E reaches lapredetermined value, the spring 19 effects only partial return movementof the regulating valve 13 to starting position to thereby reduce thelength of effective working strokes of the main piston 4.

In accordance with an important feature of the present invention, theregulating valve 13 is movable axially 0f the chamber 15 in response tobias of the return spring 19 or in response to admission of fuel throughthe duct 21, and this valve 13 is also rotatable to thereby furtherselect the exact moment when the relief bore 14 begins to communicatewith the bore 16. This specific configuration of the regulating face 18on the plunger 13b insures that the exact moment when the bores 14, 16of the relief channel 14-16 begin to communicate with each other duringa working stroke of the main piston 4 can be changed in response toangular displacement of the valve 13. The purpose of the regulating face18 on the plunger 13b is to prevent escape of fuel via bore 16 when theengine E vis started and its cylinders should receive greater quantitiesof fuel, as well as to determine the exact quantities of fuel which willbe admitted to the engine cylinders while the engine operates normally.

The regulating valve 13 can be Vcaused to change its angular position inresponse to changes in rotational speed of the engine. For example, theangular position of the valve 13 could be changed by resorting to aconventional centrifugal governor. However, in the embodiment of FIG. l,the angular position of the valve 13 is changed in response to changesin pressure produced by the fuel pump 7. This is tantamount to changesin rotational speed of the engine E because the latter includes thedrive D which operates the fuel pump 7. In order to prevent too rapidrise in pressure produced by the fuel pump 7, the struc ture of FIG. 1preferably comprises a pressure regulating unit including a pipe 26which connects to the tank 1e and bypasses the fuel pump 7. As clearlyshown in FIG. 1, the intake and discharge ends of the pipe 26 arerespectively connected with the fuel conduit 27 upstream and downstreamof the fuel pump 7 and the flow of fuel through the pipe 26 may bethrottled at 28 by means of a throttling device including a plunger 29which is permanently biassed by a helical expansion spring 30. The upperends face of the plunger 29 is subjected to the pressure of fuel so thatsuch pressure opposes the bias of the spring 30. As shown in FIG. 4, thejust described pressure regulating unit 26, 28-30 insures that thepressure p in the iirst outlet 27a of the fuel conduit 27 is a functionof the rotational speed n of the engine E.

A second outlet 27b of the fuel conduit 27 is connected to one chamber31a of a control cylinder 31 which accommodates a control piston 32, thelatter serving to change the angular position of -the regulating valve13. The operative connection between the control piston 32 and theregulating valve 13 comprises a mechanism which can convert axialmovement of the piston 32 into angular movement of the valve 13. In theembodiment of FIG. l, the just outlined mechanism comprises a pin 33which is rigid with a cupped spring retainer 34 rotatable in the suctionspace 7 and arranged coaxially with the valve 13. As best shown in FIG.5, the pin 33 passes through a radial slot 35 of the control piston 32and its outer end extends into a cylindrical head 33a which is turnableand movable radially in the slot 35 0f the control piston. This pin 33can rock the spr-ing retainer 34 in response to axial displacement ofthe control piston 32. The coupling between the spring retainer 34 andthe valve 13 comprises an axially parallel pin 36 which allows for axialmovement of the valve with reference to the spring retainer. As clearlyshown in FIG. 1, the spring retainer 34 accommodates the major part ofthe return spring 19.

In order to facilitate understanding of the operation of the motiontransmitting mechanism 33-36, the control cylinder 31 and its piston 32are shown in FIG. 1 first by solid lines and also by phantom lines. Theother chamber 31b of the control cylinder 31 is connected with the pipe26. The cylinder 31 is shown as forming an integral part of the pumphousing 1.

Referring to FIG. 5, the cylinder chamber 31a acccommodates a helicalspring 37 'which biases the control piston 32 in a direction to the leftso that it opposes the pressure of fuel admitted through the outlet 27bof the fuel conduit 27. The spring 37 yields when the fuel pressure inthe chamber 31a rises from zero (while the engine E is at a standstill)to a first value corresponding to a rotational speed during idling ofthe engine. In other words, the spring 37 will yield when the regulatingvalve 13 can begin to establish a connection between the bores 14 and 16during each working stroke of the main piston 4. The other chamber 31bof the control cylinder 31 accommodates at least one additional spring38 and/or 45 which yields when the rotational speed of the engine E andhence the fuel pressure exceeds a second value which is variable and-which is always higher than the aforementioned first value.

Referring now to FIG. 2, the regulating face 18 of the valve 13 isillustrated in developed view. This regulating face comprises a section18a which is located in a plane making right angles with the axis of thevalve 13. When the collar 13c abuts against the internal surface 1f, thedistance a between the section 18a and the inlet 39 of the relief bore16 at least equals the maximum axial stroke of the valve 13. FIG. 2shows that the section 18a is located at a considerable axial distancefrom the inlet 39, i.e., the axial position o-f the regulating valve 13corresponds to a position which the valve assumes when the collar 13aabuts against the surface 1f. The angular position of the valve 13corresponds to that which the spring retainer 34 assumes in response toa minimum fuel pressure in the cylinder chamber 31a. The abscissa of thediagram shown in FIG. 2 indicates various angular positions alpha of theregulating valve 13 and the ordinate indicates the axial distances 1covered by the valve 13 in the chamber 15. For the sake of simplicity,the regulating face 18 of FIG. 2 is assumed to be stationary and it istherefore assumed that the inlet 39 of the relief bore 16 changes itsangular positions with reference to the valve 13. In other words, whileobserving FIG. 2, one should bear in mind that it is the regulating face18 which turns about the axis of the regulating valve 13, not the inlet39.

When the relative position of the inlet 39 with reference to the section18a is such as that indicated at 39a,

the engine E is being started whereby the section 18a cannot permit flowof fuel from the circumferential groove 17 into the relief bore 16.Therefore, all of the fuel expelled from the working chamber 2 by themain piston 4 will enter one of the fuel lines 12 and will be admittedto the corresponding injection nozzles.

The regulating valve 13 may be turned by means of the control piston 32and also by hand. Such manual adjustment will be made to arrest theengine E. As illustrated in FIG. 1, the spring retainer 34 is receivedin a cupped socket 41 which is coaxial with the regulating valve 13 andis rotatable in the pump housing 1, The socket `41 is rigid with anactuating shaft 42 -which may be rotated by the driver of the vehicle,either directly or by remote control. The coupling between the springretainer 34 and the socket 41 comprises an axially parallel pin 43 whichengages a radial projection 44 of the spring retainer. In order toenable the driver to arrest the engine E, the regulating face 18 of thevalve 13 comprises a section 18b which is lparallel with and is locatedopposite the section 18a. The section 18b exposes at least aportion ofthe inlet 39 (see the latters position 39h) when the driver turns theactuating shaft 42 in order to change the angular position of the valve13. In this way, the valve 13 allows all of the fuel which is expelledfrom the working chamber 2 to flow through the relief bore 14, throughthe groove 17, inlet 39, the remainder of the relief bore 16, and backinto the suction space 6. In other words, the engine E does not receiveany fuel.

The aforementioned liquid abutment or liquid stop is effective at leastat such times when the engine operates at a maximum rotational speed.The exact rotational speed at which the liquid abutment becomeseffective can be determined by the throttle 24. In the embodiment ofFIGS. 1 and 5 to 1l the liquid abutment will become effective only whenthe engine E operates at a maximum rotational speed. FIG. 13 illustratesa modified fuel injection pump wherein the liquid abutment will becomeeffective in a plurality of speed ranges, i.e., not only when the engineis operated at a maximum speed.

In the embodiment of FIGS. 7 and S to 11, the throttle 24 is adjustedonly once in such a way that it prevents lfull expansion of the returnspring 19 only at such times when the rotational speed of the engine Ereaches a maximum value. The control piston 32 in the control cylinder31 is acted upon by three springs 37, 38 and 45. The bias of the spring45 may be selected by the driver, and the bias of this spring is weakerthan that of the spring 38, i.e., the spring 45 will yield lbefore thespring 38. As shown in FIG. 5, the control cylinder 31 accommodates apusher or plunger 46 which is slidable in the chamber 31b and has acentrally located rod 47 extending through a spring retainer 48. Thelatter is coaxial with the pusher 46 and its axial position may beadjusted to thereby change the 'bias of the spring 45. Such adjustmentmay be carried out in response to angular displacement of a pinion 50which meshes with a rack 51 provided on the spring retainer 48. Thepinion 50 is rotatable about a fixed axis by means of a lever 49.

The spring 45 is inserted between the bottom wall of the spring retainer48 and a disk 52 which latter is traversed by the rod 47. The spring 38is installed between the disk 52 and the bottom wall of the pusher 46.The rod 47 carries a stop 53 (for example, a split ring fitted into acircumferential -groove of the rod 47) which prevents excessivedisplacement of the disk 52 under the bias of the spring 38. Therightward stroke of the spring retainer 48 is limited by a second stop54.

As shown in FIG. 6, the leftmost convolution of the spring 45 can moveat a maximum distance b from the disk 52. It is assumed that theright-hand end convolution of the spring 45 is attached to the bottomwall of the spring retainer 48. If the spring 37 is contracted, thepusher 46 is spaced from the control piston 32 by a distance c. When thedisk 52 abuts against the stop 53, this disk is separated from thepusher 46 by a distance d. The spring retainer 48 has an annular centralportion or hub 48a having a recess dimensioned to accommodate the stop53 so that the disk 52 can move into direct abutment with the hub 48a.The stroke of the pusher 46 in a direction toward the control piston 32is limited by nuts 55, shown in FIG. 5, which mesh with the right-handend of the rod 47, see FIG. 5.

The fuel-injection pump shown in FIGS. 1 and 5 to 11 operates asfollows:

As stated before, the liquid abutment of this pump becomes effectiveonly when the engine E operates at a maximum rotational speed,i.e.,.when such rotational speed exceeds a predetermined value which isselected for each engine embodying the fuel injection pump. In otherwords, the position of the throttling member 25 is adjusted in advance,but such position can be changed by the linkage 49a so that the samepump may be used to inject fuel into different types of internalcombustion engines.

The length and inclination of the slanting section 18C of the regulatingface 18 on the valve 13 are selected in such a way that, depending onthe angular and axial position of such inclined section, the valve 13will admit a given quantity of fuel to the relief bore 16 whereby suchquantity varies between zero and maximum quantity, depending uponwhether the engine E is idling or operates at full load. An equalizationwill take place only when the inlet 39 of the bore 16 is controlled bythat section of the regulating face 18 which is selected to regulate theow of fuel at maximum load.

As stated before, the rotational speed (with the exception of maximumspeed) of the engine E is selected by rotating the regulating valve 13about its own axis. Such rotation can be brought about by the controlpiston 32 or by the actuating shaft 42, i.e., in response to changes inpressure produced by the fuel pump 7 or by manual adjustment of thesocket 41 through the intermediary of the actuating shaft 42. Thepressure of fuel admitted into the chamber 31a of the control cylinder31 is opposed by one, two or all three springs 37, 38, 45. The range ofrotational speeds below the aforementioned maximum rotational speedincludes a certain range in which no regulation of the rotational speedtakes place excepting by means of the shaft 42. This will be describedhereinafter.

When the engine E is at a standstill, the control unit including thecylinder` 31, piston 32, pusher 46 and springs 37, 38, 45 assumes theposition shown in FIG. 6. The spring 37 is contracted and maintains theycontrol piston 32 in the left-hand end position whereby the relativeposition between the inlet 39 of the relief bore 16 and the regulatingface 18 of the valve 13 corresponds to that shown for the inlet 39a andsection 18a of FIG. 2. The spring retainer 48 then abuts against thestop 54.

When the driver thereupon starts the engine E, the rotational speed n(see FIG. 4) does not immediately increase to such a v-alue that thepressure p of fuel discharged from the pump 7 and acting in the cylinderchamber 31a could expand the spring 37. Therefore, the inlet 39 remainssealed by the regulating valve 13 and the liquid abutment is noteffective. In other Words, each of the fuel lines 12 receives a maximumquantity of fuel expelled from the working chamber 2 by the main piston4. In FIG. 3, such maximum quantity of fuel is indicated by the line Qa.In the diagram of FIG. 3, the quantity of injected fuel is plotted onthe ordinate as a function of the angular position (angle alpha) of theregulating valve 13. The diagram of FIG. l2 is analogous; in thisillustration, the quantity of injected fuel is shown as a function ofthe rotational speed n of the engine.

When the engine E is running, the pressure p produced by the fuel pump 7rises and assumes a value which sufces to overcome the bias of thespring 37. This spring 37 determines the quantity of injected fuelduring starting. Once the bias of the spring 37 is overcome, thecomponents of the control unit assume the positions shown in FIG. 7.This is the position of the control unit during idling of the engine E.The clearances c and b are eliminated because the fuel flowing throughthe inlet 27b acts against the left-hand face of the control piston 32and displaces the latter in a direction to the right so that the piston32 abuts against the pusher 46 and the disk 52 abuts against the spring45. The springs 38 and 45 oppose further rightward movement of thepusher 46 whereby the position of the inlet 39 with reference to theregulating Iface 18 corresponds to that shown in FIG. 2 at 39C. Thespring retainer 48 continues to abut against the stop 54. Once the inlet39 assumes the position 39e of FIG. 2, only small axial displacement ofthe regulating valve 13 suices to allow for escape of fuel through therelief bore 16 in response to a working stroke of the main piston 4 andfuel displacing element 5. Therefore, the cylinders of the engine Ereceive very little fuel. This is indicated in FIG. 3 or 12 by thehorizontal line Qb.

If the operator turns the lever 49 to shift the spring retainer 48 inadirection to the left, as viewed in FIG. 7, he compresses the spring 45because the spring 38 is stiffer and, during such adjustment of thespring retainer 48, the spring 38 acts not unlike a rigid body. It isassumed that the lever 49 has been rocked to select a satisfactoryquantity of fuel for partial load at low rotational speed and that thespring retainer 48 then takes the Iposition shown in FIG. 8. The spring45 is biased and displaces the control piston 32 against the action offluid pressure in the chamber 31a. This takes place when the rotationalspeed of the engine is relatively low. Of course, the control piston 32changes the angular position of the regulating valve 13 so that theinlet 39 of the relief bore 16 assumes the relative position 39d of FIG.2. The quantity of fuel which is injected into the cylinders of theengine E then corresponds only to a fraction of the maximum fuelquantity. Such position of the control piston 32 corresponds to a givenrotational speed which again causes the pump '7 to produce apredetermined fuel pressure acting against the left-hand end face of thecontrol piston 32. If the rotational speed rises above that which isdesired by the operator of the vehicle, the control piston 32 moves in adirection to the right, as viewed in FIG. 8, because the fuel pressurein the chamber 31a rises. The disk 52 moves nearer to lbut does not asyet abut against the hub 48a of the spring retainer 48. In other words,the spring 45 yields but is not fully compressed so that the disk 52assumes an intermediate position between the positions shown in FIGS. 8and 9. Such axial displacement of the control piston 32 toward thespring retainer 48 causes the regulating valve 13 to change its angularposition and to reduce the quantities of fuel which are injected intothe engine cylinders during successive working strokes of the mainpiston 4. Under certain circumstances, hte quantity of injected fuel canbe reduced to match that during idling. The downwardly inclined lines m'shown in FIG. l2 indicate such type of regulation which is not due tothe liquid abutment but rather to the regulating action of the face 18on the valve 13.

FIG. 12 shows a rotational speed n1 starting from which the pressure offuel -against the left-hand end face of the control piston 32 risessufficiently to effect such compression of the spring 45 that the disk52 comes into actual contact with the hub 48a of the spring retainer 48.The spring 45 is then lfully compressed. If the operator thereupon rocksthe lever 49 to such an extent that the spring retainer 48 assumes itsleft-hand end position shown in FIG. 9, the control piston 32 assumes aposition in which the relative angular position of the inlet 39 withreference to the regulating face 18 of the valve 13 is such as shown inFIG. 2 by the broken-line circle 39e. This is a position correspondingto maximum load. The quantity of injected fuel in such relative positionof the inlet 39 and face 18 is indicated in FIGS. 3 and 12 by horizontallines Qe.

It is also possible that, when the spring 45 is fully compressed, thespring retainer 48 assumes the position shown in FIG. 8 whichcorresponds to partial load. In such situation, the quantity of injectedfuel is as indicated by the points Qd in FIG. 12. Each point Qdcorresponds to a different position of the spring retainer 48, i.e., toa different position of the lever 49. Such positions of the lever 49 areselected by the operator of the vehicle. In each instance, the spring 45is fully compressed when the rotational speed of the engine E reachesthe value n1.

If the rotational speed exceeds the value nl, the control piston 32 canbe displaced only by the small distance rl, namely, until the disk 52comes into actual abutment with the pusher 46 and effects fullcompression of the spring 38. The piston 32 then takes the positionshown in FIG. 10, it being assumed that the lever 49 maintains thespring retainer 48 in the left-hand end position. This short distance dis represented in FIG. 12 by the sloping lines q.

Aside from such minor adjustment in response to reduction of thedistance d to zero, there is no other adjustment in the quantity ofadmitted fuel when the rotational speed rises above the value nl but isless than such rotational speed at which the liquid -abutment becomeseffective to prevent undersirable increase in the rotational speed. Theeffect of the liquid abutment is illustrated in FIG. 12 by the slantingline r.

In order to terminate the injection of fuel, the operator returns thespring retainer 4S to the right-hand end position, namely, into abutmentwith the stop 54 as shown in PIG. l1. This is the starting position ofthe member 48, see lalso FIG. 6. At the same time, the operator turnsthe shaft 42 in order to shift the control piston 32 and pusher 46 tothe right-hand end position whereby the spring 37 expands. The positionof the inlet 39 with reference to the regulating face 18 of the valve 13is then such as indicated in FIG. 2 by the broken-line circle 39b. Thisprevents admission of any fuel into the cylinders of the engine Ebecause the fuel which is expelled from the working chamber 2 caninvariably ilow through the relief bore 14 and back to the suction space6.

The control piston 32 can assume the position of FIG. l1 when therotational 'speed of the engine E increases while the spring retainer 48remains in the starting position of abutment against the stop 54. Thiscan happen when the vehicle travels downhill. The pressure p at thedownstream side of the fuel pump 7 then rises -as shown in FIG. 4 andthe piston 32 yields to such pressure to move to the position shown inFIG. 1l.v In other words, the injection of fuel is terminated in a fullyautomatic way In the embodiment of FIG. 13, the position of thethrottling member (see FIG. 1) is adjustable by the linkage 49a. Thus,the operator can select that rotational speed n of the engine E at whichthe liquid abutment becomes effective. In this embodiment, too, thespring 38 determines the maximum quantity of injected fuel in dependencyon the rotational speed of the engine.

The control piston 32a of FIG. 13 has an axially extending stud 57 whichcarries a slidable disk 62. The outward movement of the disk 62 islimited by a stop 63 at the free end of the stud 57. The spring 38 isinstalled between the disk 62 and an Linternal surface of the piston32a. An adjustable stop 58 can arrest the disk 62 but allows for furtherrightward movement of the piston 32a.

The operation of the fuel injection pump which embodies the control unitof FIG. 13 is as follows:

Each position of the throttling member 2S corresponds to a differentrange of rotational speeds n. Each such range is controlled by theliquid abutment. In other words, the drive can select the rate of fuelflow through the return duct 23 by changing the position of the linkage49a shown in FIG. l, and each position of the linkage 49a corresponds toa different range of rotational speeds. The total quantity of fueldelivered by the main piston 4 will be injected into the cylinders ofthe engine E until the liquid stop becomes effective. The face 18 of theregulating valve 13 corrects only the maximum amount of fuel independency on the rotational speed n. The effect of the regulating face18 is relatively small and corresponds to the inclination of the curvewhich indicates in FIG. 14 or 16 the quantity Q of injected fuel. Thistakes place between the rotational speed n2 (when the starting operationis completed and the cylinders of the engine need not receive a maximumamount of fuel) when the compression of the spring 3S shown in FIG. 13begins, and the rotational speed n3 at which the piston 32a abutsagainst the disk 62 and the latter engages the stop 58. In the diagramsof FIGS. 14 and 16, the quantity Q of the injected fuel is plotted alongthe ordinate and the rotational speed n of the engine is plotted alongthe abcissa, the same as in FIG. 12. It will be seen that the quantity Qmay be varied with the type of engine in such a way (FIG. 16) that thequantity Q increases with increasing speed n or that the quantity Qdecreases (FIG. 14) when the rotational speed n increases. The diagramof FIG. 15 is similar to that of FIG. 16 with the distinction that theangle alpha is measured along the abscissa. In FIGS. 14 and 16, theaction of the liquid abutment is indicated by the inclined lines s.

Referring again to FIG. 13, the disk 62 abuts against the stop 58 butthe control piston 32a is illustrated in an axial position whichcorresponds to that when the injection of larger quantity of fuel forstarting is already terminated. Before the admission of such largerquantities of fuel for starting is terminated, and particularly when theengine is idle, the disk 62 is separated from the stop 58 by a gapcorresponding to the gap c shown in FIG. 6.

It will be seen that an important feature of -my invention resides inthe provision of a fuel injection pump whose regulating valve 13 maychange its angular position in response to changes in rotational speed11 of the engine E, namely, in response to changes in axial position ofthe control piston 32 or 32a as a function of fuel pressure generated bythe auxiliary pump 7, such fuel pressure being a function of therotational speed of the engine. While the rotational speed n of theengine rises from zero speed to idling speed (first range of rotationalspeeds), the valve 13 completely seals the relief conduit 14-16 whichincludes the bores 14, 16 so that all of the fuel expelled from theworking chamber 2 while the main piston 4 performs a working strokeenters one of the fuel lines 12, i.e., the discharge conduit includingthe axial groove 11 of the main piston 4 and one of the fuel lines 12.In other words, when the rotational speed n reaches the idling speed,the first spring 37 of the resilient means 37, 38, 45 or 37, 38 yieldsto fuel pressure to allow for axial displacement of the control piston32 or 32a. The additional spring 45 and/ or 38 yields when therotational speed n rises to a higher second value, and the force (bias)of at least one of these additional springs 38, 45 is adjustable by thelever 49 or by turning of the adjustable stop 58 to effect axialmovement of this stop.

In the embodiment of FIGS. 1 and 5 to 1l, the bias of the spring 38 isstronger than that of the spring 45, and the bias of the spring 45 isadjustable by the lever 49 to effect change in the rate of fuel flow tothe cylinders of the engine when the latter is operated under partialload. This insures that the quantity of fuel which is injected into thecylinders of the engine when the latter operates under partial load neednot be regulated by means of the throttle 24 (linkage 49a), In otherwords, in the partial load range, the rate of fuel flow to the cylindersof the engine if effected in response to changes in angular position ofthe regulating valve 13 rather than in response to changes in theposition of the throttling member 25.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledgereadily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of my contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is:

1. In a fuel injection pump for supplying metered quantities of fuel tothe cylinders of an internal combustion engine, a source of fuel;housing means having a working chamber and a relief channel connectedwith said working chamber and including a regulating chamber; a supplyconduit adapted to connect said source with said working chamber; atleast one discharge conduit adapted to connect said working chamber witha cylinder of the engine; a main piston movable in said housing means toperform alternating suction and working strokes to thereby respectivelydraw fuel from said source into said working cha-mber via said supplyconduit and eX pel fuel from said working chamber; drive means forrorating and reciprocating said piston at a rate proportional with therotational speed of the engine; a regulating valve installed in saidregulating chamber for axial and angular movement to thereby control theow of fuel from said working chamber via said channel; an auxiliary pumpoperating in synchronism with said piston to feed fuel into saidregulating chamber during working strokes of said piston and to therebyeffect axial movement of said valve; and control means comprising a fuelpump driven by sai-d engine and arranged to raise the fuel pressure inresponse to increasing rotational speed of the engine, and a device forchanging the annular position of the valve in response to change in saidfuel pressure, said device comprising a control cylinder, a controlpiston, reciprocably received in said control cylinder, an operativeconnection between said control piston and said valve for rotating thevalve in response to reciprocation of said control piston, an outletconnecting the pressure side of said fuel pump with said controlcylinder at one side of said control piston so that the pressurized fueltends to move said control piston in one direction, and resilient meansfor biasing said control piston in the other direction and including arst spring which opposes the fuel pressure against said control pistonwithin a first range of relatively low rotational speeds of the engine,and at least one additional spring which opposes the fuel pressureagainst said control piston within a second range of relatively highrotational speeds of the engine.

2. A structure as set forth in claim 1, wherein said first range coversrotational speeds during idling of the engine.

3. A structure as set forth in claim 1, further comprising means forchanging the opposition of said additional spring to thereby change saidsecond range of rotational speeds.

4. A structure as set forth in claim 1, wherein said resilient meansincludes two additional springs each ar ranged to oppose the fuelpressure against said control piston with a different force higher thanthe force of said first spring.

5. A structure as set forth in claim 4, wherein one of said additionalsprings is weaker than the other additional spring and furthercomprising means for changing the force of said one additional spring,said valve being arranged to change the rate at which the fuel escapesfrom said working chamber via said relief channel in response torotation by said control piston while said control piston overcome theopposition of said one additional spring.

6. A structure as set forth in claim 1, wherein said regulating valvecomprises a peripheral controlling face controlling flow of fuel fromsaid working chamber via said channel, said controlling face extendingin part inclined to the axis of said valve.

References Cited UNITED STATES PATENTS 3,114,321 12/1963 Bessiere 103-413,122,100 2/1964 Bessiere 103-41 3,157,173 11/1964 Martyn.

MARTIN P. SCHWADRON, Primary Examiner.

